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Topic: ic pistons (Read 1469 times)

I have been having problems with chilled cast iron on the skirt of the ci piston provided for the Centaur gas engine.After the advice received I have heated the casting four times now and the chilled area has reduced each time but is 1/4" now.I want to know if I can use a steel piston as it will have cast iron piston rings running in a cast iron cylinder,or will differing expansion rates be a problem.Frank

Should not be a problem, you can always make allowance for any expansion in the size of the piston.

Using cast iron bar or even aluminium would make for easier machining, Quite a few of the hit and miss engines I have made have aluminium pistons and don't have problems with expansion, just allow about 0.0025" per 1" dia of piston.

Frank, most of my hot air engines have pistons made from old window weights. My pistons normally have a skirt about 1 mm to 1.5 mm thick, and a crown about 3 mm thick, There is one on the work bench that was just too thin, it broke when I was putting the labrynth grooves around it .25 mm deep. They wear well with little or no lubrication.Ian S C

Its a common thing on a lot of engines. The width of the slot inside the piston is wider than the width of the small end bearing so things can line themselfs up. So in the case of the Centaur you have a 3/4" gap and a 5/8" width of bearing, both these sizes are on the drawing